Crosslinking method

ABSTRACT

The invention provides a method of preparing a crosslinked polymer, which method comprises polymerising branched polyunsaturated monomers by a metathesis polymerisation reaction, wherein the branched polyunsaturated monomers contain acyclic ethylenically unsaturated groups that are capable of undergoing polymerization by a metathesis reaction such that the metathesis polymerisation produces a crosslinked polymer and substantially no non-volatile ethylenically unsaturated by-products.

FIELD OF THE INVENTION

The present invention relates to a method for preparing crosslinkedpolymers, and to crosslinked polymers prepared by the method. Theinvention also relates to precursor compositions that can be crosslinkedin accordance with the method, and to a method for preparing compoundsthat can be used to prepare the crosslinked polymers. The method forpreparing the crosslinked polymers is particularly suited for use inpolymer-based coating and adhesive applications, and accordingly it willbe convenient to hereinafter describe the invention with reference tothese applications. However, it is to be understood that the method mayalso be employed in other applications.

BACKGROUND OF THE INVENTION

Crosslinked polymers can generally be characterised as a network ofpolymer chains in which at least some of the chains are connectedthrough a bridging group. The nature of the bridging can varysignificantly, as can the manner in which the bridging group forms itsconnection with the polymer chains. The number of bridging groupspresent, that is the degree of crosslinking, in a crosslinked polymercan also vary significantly, with the effective molecular weight,viscosity and solubility of the polymer changing as the degree ofcrosslinking in the polymer increases. Polymers with any significantdegree of crosslinking are generally substantially insoluble insolvents.

Crosslinked polymers typically exhibit superior physical and mechanicalproperties compared to their non-crosslinked counterparts. Theproperties of polymer-based coatings and adhesives (i.e. paints,adhesives, fillers, primers and sealants etc) can therefore alsogenerally be improved by providing such products with a crosslinkedpolymeric structure. However, due to their crosslinked polymerstructure, crosslinked polymers are generally not capable of beingapplied to a substrate in a manner that is required for the applicationof most coatings and adhesives. In particular, crosslinked polymerscannot generally be moulded into a desired shape or applied as a layeronto the surface of a substrate.

To provide polymer-based coatings and adhesives with a crosslinkedstructure and an ability to be readily applied to a substrate, theproducts are often formulated such that crosslinking occurs after theproduct has been applied to the substrate. One of the more commonformulating techniques used to achieve such post-applicationcrosslinking is to provide the product with at least one polymer whichcontains reactive functional groups. The reactive functional groupsafford sites that can react and promote crosslinking post-application ofthe product.

One approach to providing such products with these reactive functionalgroups has been to formulate them with unsaturated natural oils (eg.glyceride oils), or alkyd resins formed therefrom. Compositionsformulated with these materials make up a large percentage of coatingsused globally and are commonly referred to as air-dry enamels or oilbased paints. Drying or curing of such paints essentially results fromthe reaction of atmospheric oxygen with the ethylenically unsaturatedgroups derived from the oils, which in turn promotes crosslinking of thecomposition in a process known as autoxidation.

However, despite being effective at forming crosslinked polymerstructures, the autoxidation process is particularly slow. Sufficientcrosslinking necessary to apply a second coat of paint withoutdisturbing the first can only be achieved after the film has beenallowed to dry over night. Even then, a range of environmental factorssuch as temperature and humidity can retard the rate of drying.

The process of autoxidation can also continue for a long period of time(i.e. post drying of the paint) and may result in degradation of thephysical properties of the paint film. This degradation can limit theperformance of such coatings, particularly in an exterior environment.Oil based paints are also prone to yellowing in the absence of directsunlight. The tendency for these paints to yellow is believed to stemfrom a variety of atmospheric based reactions of residual unsaturationderived from the fatty acid segments of the polymer.

An alternative approach to providing such products with these reactivefunctional groups has been to formulate them with a polymer thatcontains functional groups that will react with water. In this case, theproducts can be formulated to form a crosslinked structure afterapplication through being exposed to atmospheric moisture. However, dueto their inherent moisture sensitivity, great care needs to be taken toexclude moisture during the manufacture, packaging and storage of suchproducts. Despite exercising care to exclude moisture from the products,moisture cure products often have a limited shelf-life.

Coatings and adhesives are also commonly provided in a two-part formwhere one part includes a polymer which contains functional groups thatare reactive toward functional groups of a polymer contained in theother part. In this case, each part is mixed prior to application, andcrosslinking occurs post-application through reaction of the respectivefunctional groups provided from each part. The two-part coating andadhesive formulations have the advantage of being generally lesssensitive to moisture and therefore often have a good shelf-life.However, by virtue of their reactivity, the individual components cannotbe provided in the form of a single-part composition, as would be mostconvenient. Furthermore, once the two parts are mixed the product mustbe used within a relatively short time frame.

Although the aforementioned moisture cure and two-part coating andadhesive products effectively form post-application crosslinkedpolymeric structures, the reactive functional groups used to provide thecrosslinking sites can render the products toxic. For example, reactivefunctional groups commonly used in such products include isocyanates,amines, epoxides and cyano acrylate esters, Accordingly, there can beoccupational health and safety risks associated with both themanufacture and use of such products. Furthermore, the monomerscomprising the reactive functional groups used in such products aregenerally relatively expensive.

Another common formulating technique used to achieve post-applicationcrosslinking is to provide products in a two-part form where one partcontains a radical initiator and the other part contains a crosslinkablepolymer composition. In this case, the initiator is mixed with thepolymer composition prior to application, the mixture is then generallyimmediately applied to a substrate and crosslinking occurspost-application through a radical mediated crosslinking reaction thatis promoted by the initiator. As with the previous formulatingtechniques, this technique also provides for an effective means toachieve post-application crosslinking. However, such polymercompositions are prone to premature and spontaneous crosslinking, theprocess of which is very exothermic and potentially explosive. Thesepolymer compositions therefore typically need to be formulated withinhibitors to prevent this. Despite the use of inhibitors, the polymercompositions often have a limited shelf-life. Furthermore, initiatorscommonly used in these products, such as those which contain a peroxylinkage, are typically quite toxic and potentially explosive in theirown right.

Accordingly, there remains a need to provide an alternative method forpreparing crosslinked polymers that can overcome or alleviate at leastsome of the disadvantages associated with the aforementioned methods.

SUMMARY OF THE INVENTION

The present invention provides a method of preparing a crosslinkedpolymer, which method comprises polymerising branched polyunsaturatedmonomers by a metathesis polymerisation reaction, wherein the branchedpolyunsaturated monomers contain acyclic ethylenically unsaturatedgroups that are capable of undergoing polymerisation by a metathesisreaction such that the metathesis polymerisation produces a crosslinkedpolymer and substantially no non-volatile ethylenically unsaturatedby-products.

Typically, the branched polyunsaturated monomers referred to herein willcomprise an atom or core to which is attached at least three moieties,at least three of which contain one or more acyclic ethylenicallyunsaturated groups that are capable of undergoing polymerisation by ametathesis reaction.

It has now been found that branched polyunsaturated monomers can bepolymerised by a metathesis pathway to afford a crosslinked polymerstructure. The method of the invention is particularly suited forpreparing crosslinked polymers that can be used in polymer-basedcoatings and adhesives, and can be readily employed to providepost-application crosslinking.

As will be discussed in more detail below, the branched polyunsaturatedmonomers can also be polymerised in conjunction with other unsaturatedmonomers such as diene monomers.

Those skilled in the art will appreciate that metathesis polymerisationreactions afford a polymer product and an ethylenically unsaturatedcompound as by-product. In forming crosslinked polymers in accordancewith the invention, it is important that the metathesis polymerisationaffords substantially no non-volatile ethylenically unsaturatedby-products. In other words, in addition to the crosslinked polymer,substantially all by-products of the metathesis polymerisation arevolatile ethylenically unsaturated by-products. By being volatile, theethylenically unsaturated by-products can be more readily separated fromthe reaction mixture. This not only promotes formation of thecrosslinked polymer, but advantageously also allows for the crosslinkedreaction product to be effectively used in, for example, paint,adhesive, filler, primer and sealant products etc (hereinafter simplyreferred to as coating(s) and adhesive(s) or coating and adhesiveproducts).

Formation of non-volatile ethylenically unsaturated by-products in themetathesis polymerisation reaction is likely to result in thecrosslinked reaction product being unsuitable for use as coating andadhesive products. In particular, the presence of such non-volatileethylenically unsaturated by-products in coatings and adhesives canprevent them from drying (i.e. they remain tacky), can reduce or inhibittheir adhesive or bonding properties, and can in general reduce theirphysical and/or mechanical properties.

It will be appreciated that whether a given ethylenically unsaturatedby-product is non-volatile or volatile will be dependant on both thepressure and temperature at which this property is assessed. In thecontext of the invention, the terms “non-volatile” and “volatile” arenot intended to refer to absolute qualities of a given ethylenicallyunsaturated by-product, but rather they are to be used as a practicalguide in considering the suitability of crosslinked polymer for use as acoating or adhesive. Thus, those metathesis polymerisation reactionsthat afford substantially no non-volatile ethylenically unsaturatedby-products are likely to provide crosslinked polymers that are suitablefor use as coatings or adhesives. In this context, “substantially no”will generally mean less that 15 wt %, preferably less than 10 wt %,more preferable less than 5 wt % of non-volatile ethylenicallyunsaturated by-products, relative to the total mass of ethylenicallyunsaturated by-products produced by the metathesis polymerisationreaction.

As a convenient point of reference only, in the context of coatings andadhesives, a person skilled in the art might consider the ethylenicallyunsaturated by-products to be “non-volatile” if they are not vaporisedat atmospheric pressure from a coating or adhesive comprising acrosslinked polymer formed in accordance with the invention at (1) roomtemperature (ca. 15-35° C.) within 24 hours, (2) about 150° C. withinabout 10 minutes, or (3) about 230° C. within about 30 seconds (i.e.common drying regimes for using such products).

Alternatively, as a convenient point of reference only, in the contextof coatings and adhesives a person skilled in the art might consider theethylenically unsaturated by-products to be “non-volatile” if theycontained more than about 12 carbon atoms. In other words, theethylenically unsaturated by-products preferably contain 2 to about 12,more preferably 2 to about 9 carbon atoms.

Accordingly, the present invention further provides a method ofpreparing a crosslinked polymer suitable for use as or as part of acoating or adhesive, which method comprises polymerising branchedpolyunsaturated monomers by a metathesis polymerisation reaction,wherein the branched polyunsaturated monomers contain acyclicethylenically unsaturated groups that are capable of undergoingpolymerisation by a metathesis reaction such that the metathesispolymerisation produces a crosslinked polymer.

A notable advantage provided by the invention is that the crosslinkedpolymers may be prepared from a diverse array of monomers. Inparticular, the monomers used need only contain relatively inert acyclicethylenically unsaturated groups. Thus, such monomers will generally beless toxic than those used to prepare conventional crosslinked polymers,and also generally less prone to premature spontaneous crosslinking.Furthermore, suitable monomers may be provided from relativelyinexpensive sustainable resources such as natural oils.

In preparing the crosslinked polymers in accordance with the invention,it may be preferable to use branched polyunsaturated monomers thatcontain terminal or near terminal acyclic ethylenically unsaturatedgroups. By using such monomers, formation of non-volatile ethylenicallyunsaturated by-products can advantageously be reduced if notsubstantially avoided. By the expression “terminal or near terminal” ismeant that the acyclic ethylenically unsaturated groups can be locatedat the end of an organic moiety (i.e. a vinyl group), or within 6 atoms,preferably within 4 atoms from the end of such a moiety. For example,the unsaturated group(s) may be located within 6 carbon atoms at the endof an organic moiety designated R, i.e. R—C═C—C—C—C—C, R—C—C—C═C—C—C,R—C—C—C—C═C—C, or R—C—C—C—C—C═C.

Branched polyunsaturated monomers that contain terminal or near terminalacyclic ethylenically unsaturated groups may be prepared by any suitablemeans. However, the use of cross-metathesis reactions to prepare thesemonomers has been found to be particularly convenient.

Accordingly, the invention also provides a method of preparing acrosslinked polymer, which method comprises:

-   -   1) preparing branched polyunsaturated monomers having terminal        or near terminal acyclic ethylenically unsaturated groups that        are capable of undergoing polymerisation by a metathesis        reaction, by subjecting a compound comprising one or more        acyclic ethylenically unsaturated groups to a cross-metathesis        reaction with a low molecular weight ethylenically unsaturated        compound to produce a compound comprising one or more terminal        or near terminal acyclic ethylenically unsaturated groups which:        -   (a) can be used as the branched polyunsaturated monomers,            and/or        -   (b) is reacted with one or more other compounds to provide a            compound which can be used as the branched polyunsaturated            monomers; and    -   2) polymerising the branched polyunsaturated monomers by a        metathesis polymerisation reaction to afford the crosslinked        polymer.

Through use of such a cross metathesis reaction pathway, branchedpolyunsaturated monomers derived from inexpensive natural oils canadvantageously be used to prepare unique crosslinkable coatings andadhesives. Notably, such methodology enables many so called non-dryingor semi-drying natural oils, that have to date been unsuitable for usein coatings and adhesives, to now be used. For example, mono unsaturatedtriglycerides (i.e. one double bond in each fatty acid arm of thetriglyceride) can be readily employed to prepare crosslinkable coatingsand adhesives.

The invention therefore also provides a coating (such as a paint) oradhesive product comprising branched polyunsaturated monomers thatcontain acyclic ethylenically unsaturated groups that are capable ofundergoing polymerisation by a metathesis reaction to form a crosslinkedpolymer, and an olefin metathesis catalyst.

Other aspects of the invention are described below.

DETAILED DESCRIPTION OF THE INVENTION

Unless otherwise stated, where the term “acyclic” is used herein inconjunction with expressions such as “diene monomer”, “ethylenicallyunsaturated group”, or “ethylenic unsaturation”, or similar expressions,it is intended for this to be a reference to the nature of theunsaturated character of that group or monomer rather than any otherfacet of that monomer or moiety which contains that group. Thus, amoiety containing an “acyclic” ethylenically unsaturated group may alsocontain cyclic groups, but the ethylenically unsaturated group per se isacyclic in character in that it is not contained within a cyclicstructure. In the case of an “acyclic” diene monomer, only theethylenically unsaturated groups need be acyclic in character.

The polymerisation of acyclic diene monomers by metathesis is generallywell known and is commonly referred to as ADMET (acyclic dienemetathesis) polymerisation. As with all metathesis reactions, ADMETpolymerisation involves the reaction of a transition metal alkylidenecomplex, more commonly referred to as an olefin metathesis catalyst,with an acyclic ethylenically unsaturated group. Mechanistically,propagation of a polymer chain by ADMET polymerisation is believed toinvolve the formation of two metallocyclobutane intermediate species,with the polymer chain being ejected from the active metal speciesduring each propagation step. The propagation step also involves theliberation of an ethylenically unsaturated reaction by-product,preferably a volatile molecule such as ethylene, which needs to beremoved from the reaction environment to promote polymerisation.

ADMET polymerisation reactions inherently afford polymers with a linearunsaturated backbone. Studies have shown that the unsaturated characterof these polymers may be used in secondary reactions to providecrosslinking sites. In particular, polymers derived from ADMETpolymerisation reactions have been subjected to conventional thermal,ultraviolet and chemical modification processes to afford crosslinkedpolymer structures (Macromolecules, 1992, 25, 2049-2052).

It has now been found that a metathesis reaction pathway can be used todirectly prepare crosslinked polymers in an effective and efficientmanner,

In accordance with the invention, crosslinked polymers can be preparedby polymerising branched polyunsaturated monomers. The branchedpolyunsaturated monomers will typically have at least one atom or coreto which is attached at least three moieties, at least three of whichcontain acyclic ethylenic unsaturation. The atom or core may have morethan three moieties attached to it, and more than three moieties maycontain acyclic ethylenic unsaturation.

To more clearly describe what is intended by the branchedpolyunsaturated monomers having “an atom or core to which is attached atleast three moieties”, the monomers can be conveniently represented ascomprising at least the general structural unit (I):

BR¹R²R³   (I)

where B represents an atom or core, and where each moiety R¹, R² and R³,which may be the same or different, contains at least one acyclicethylenically unsaturated group which is capable of undergoingpolymerisation by a metathesis reaction.

The atom or core (B) must be cable of having at least three moietiesattached to it, and as such may simplistically be viewed as a branchpoint or junction. The branched polyunsaturated monomers used inaccordance with the invention may have more than one such branch pointor junction. In this case, the further branch point(s) or juncture(s)may be provided by other atoms or cores present in one or more of themoieties attached to the atom or core (B) in general structural unit(I). Accordingly, the branched polyunsaturated monomers may compriseboth atoms and cores that provide for branch points or junctions.

Where B in the general structural unit (I) is an atom, it will generallybe C, Si or N. In the case where the atom is C or Si, the branch atommay have a fourth moiety attached to it which can also contain at leastone acyclic ethylenically unsaturated group that is capable ofundergoing polymerisation by a metathesis reaction.

By the term “core”, as used in connection with the branchedpolyunsaturated monomers, is meant a molecular structure to which the atleast three moieties are attached. For example, the core might be acyclic aromatic or non-aromatic structure such as that afforded by abenzene or cyclohexane ring, fused derivatives thereof, or possibly acollection of such cycles coupled together by alkyl groups. The coremight also be an oligomeric or polymeric structure. In contrast with thegeneral structural unit (I) in which B is an atom, where B is a “core”the number of moieties which contain at least one acyclic ethylenicallyunsaturated group that can be attached to the core can be considerablyhigher than four.

As mentioned above, the branched polyunsaturated monomers will typicallycomprise at least three moieties attached to an atom or core, each ofwhich contain at least one acyclic ethylenically unsaturated group thatis capable of undergoing polymerisation by a metathesis reaction. Byhaving the ethylenically unsaturated groups configured in this manner,the monomers can advantageously be polymerised by a metathesis reactionto directly afford a crosslinked polymer. In contrast, polymerisation ofacyclic diene monomers through a conventional ADMET polymerisationreaction inherently affords polymers having a linear backbone.

Where an acyclic ethylenically unsaturated group is said to be “capableof undergoing polymerisation by a metathesis reaction” or reference isgiven to a crosslink reaction occurring “through a metathesis mediatedreaction pathway”, it is intended for these statements to mean that theacyclic ethylenically unsaturated groups of the monomer can react ordoes react with a metathesis catalyst in the process of forming acrosslinked polymer structure.

Those skilled in the art will appreciate the factors that may effect thesusceptibility of a given acyclic ethylenically unsaturated group toundergo polymerisation by a metathesis reaction. For example, moietieswhich contain the acyclic ethylenically unsaturated groups can impartsteric and/or electronic effects that influence the reactivity of theunsaturated groups toward a metathesis catalyst. Furthermore, and asdiscussed above, to promote the metathesis reaction the ethylenicallyunsaturated by-product of the reaction, which is itself derived from themonomers being polymerised, should be sufficiently volatile so that itcan be removed from the reaction medium.

Generally, the susceptibility of an acyclic ethylenically unsaturatedgroup to undergo polymerisation by a metathesis reaction can be enhancedby reducing steric crowding in the general proximity of the unsaturatedgroup. It may therefore be preferable that the ethylenically unsaturatedgroup contained in each of the at least three moieties attached to theatom or group is a terminal or near terminal acyclic ethylenicallyunsaturated group, and possibly an unsubstituted terminal or nearterminal acyclic ethylenically unsaturated group.

To reduce, if not substantially avoid, the formation of undesirablenon-volatile ethylenically unsaturated by-products during the course ofthe crosslinking reaction, it can be preferable that substantially allof ethylenically unsaturated groups in the monomer are terminal or nearterminal acyclic ethylenically unsaturated groups, and possiblyunsubstituted (i.e. —CH═CH— or —CH═CH₂) terminal or near terminalacyclic ethylenically unsaturated groups.

With an understanding of the function of the acyclic ethylenicallyunsaturated groups and how they might be configured within the branchedmonomers, those skilled in the art will also appreciate that apart fromthe acyclic unsaturated group itself, the structure and composition ofthe remainder of the monomer is not particularly important with respectto the crosslinking process. Accordingly, any organic group cangenerally function as a moiety provided it can be attached to an atom orcore and contains at least one acyclic ethylenically unsaturated groupwhich is susceptible to undergoing polymerisation by a metathesisreaction. The moieties may therefore comprise cyclic and/or branchedand/or linear groups, contain or be substituted with a variety offunctional groups, contain one or more hetero atoms such as N, O, S, Petc., and as mentioned above, may even contain one or more further atomsor cores (B) as hereinbefore defined.

One advantage afforded by the invention is that the crosslinked polymersmay be prepared using a diverse array of branched polyunsaturatedmonomers. Having regard to the forgoing, those skilled in the art couldreadily select suitable monomers. The monomers may have a relatively lowmolecular weight or can include oligomeric and polymeric compounds. Forexample, a branched polyunsaturated pre-polymer may be used prepare thecrosslinked polymer.

Oligomeric or polymeric branched polyunsaturated monomers that can beused in accordance with the invention may have quite complex structures.For example, the monomers may be in the form of a polymer/oligomer thathas a branched or linear backbone onto which is attached at least threemoieties as pendant groups, wherein at least three of the pendant groupseach contain at least one acyclic ethylenically unsaturated group thatis capable of undergoing polymerisation by a metathesis reaction. Inpractice, such a polymer/oligomer backbone may contain many of thesependant groups, for example greater than 20.

Polymeric/oligomeric branched polyunsaturated monomers may be preparedusing conventional polymerisation techniques such as free radical andcondensation and metathesis polymerisation techniques.

One such approach might be to prepare the polymericloligomeric branchedpolyunsaturated monomers using monomers that when polymerised affordpendant groups which contain the requisite unsaturated character. Inthis case, the mode of polymerisation that is used should enable thependant groups to retain the requisite unsaturated character.

An alternative approach might be to prepare a polymer/oligomer which hasreactive functional groups that may be subsequently reacted to providependant groups having the requisite unsaturated character. For example,a styrene maleic anhydride copolymer may be prepared by conventionalmeans and subsequently reacted with a reagent such as undecylenicalcohol to afford pendant groups with the requisite unsaturatedcharacter.

In both of the approaches mentioned directly above, the number ofpendant groups that are attached to the polymer backbone can beadvantageously varied through variation of the ratios of monomers usedto prepare the polymer/oligomer.

The branched polyunsaturated monomers used in accordance with theinvention may also be prepared directly or indirectly throughcross-metathesis reactions. For example, to provide branchedpolyunsaturated monomers which contain terminal or near terminal acyclicethylenically unsaturated groups, a compound comprising one or moreacyclic ethylenically unsaturated groups could be subjected to across-metathesis reaction with a low molecular weight ethylenicallyunsaturated compound. Such compounds would not generally alreadycomprise three or more terminal or near terminal acyclic ethylenicallyunsaturated groups.

The compound comprising one or more acyclic ethylenically unsaturatedgroups may be a branched polyunsaturated compound having an atom or coreto which is attached at least three moieties, at least three of whichcontain one or more acyclic ethylenically unsaturated groups, forexample a natural oil. In this case, the cross-metathesised productwould be a branched polyunsaturated monomer that contains terminal ornear terminal acyclic ethylenically unsaturated groups and could be usedto prepare a crosslinked polymer in accordance with the invention. Theresulting branched polyunsaturated monomer might also be reacted withone or more other compounds or reagents, for example to build themolecular weight of the compound (i.e. to form a pre-polymer). This“modified” branched polyunsaturated monomer might then be used toprepare a crosslinked polymer in accordance with the invention.

A specific example of a cross-metathesis reaction described directlyabove would be the cross-metathesis reaction of a vegetable oil withethene as shown below.

The compound comprising one or more acyclic ethylenically unsaturatedgroups may also be a branched polyunsaturated compound as describeddirectly above but in the form of a pre-polymer. For example, thecompound might be an alkyd resin prepared from the reaction of amonoglyceride with phthalic anhydride. The resin may be subjected to across-metathesis reaction with a low molecular weight ethylenicallyunsaturated compound to afford an alkyd resin comprising terminal ornear terminal acyclic ethylenically unsaturated groups that could thenbe used to prepare a crosslinked polymer in accordance with theinvention. An idealised structure of such an alkyd monomer is shownbelow.

Alternatively, the cross-metathesis reaction might be used to prepare aprecursor compound that can be reacted with one or more compounds toform a branched polyunsaturated monomer that may be used to prepare acrosslinked polymer in accordance with the invention. For example, thecompound comprising one or more acyclic ethylenically unsaturated groupsmay be a fatty acid or fatty acid ester derived from natural oils. Sucha compound could be subjected to a cross-metathesis reaction with a lowmolecular weight ethylenically unsaturated compound to afford a terminalor near terminal ethylenically unsaturated fatty acid or fatty acidester. The resulting compound could then be reacted with one or morecompounds to afford the branched polyunsaturated monomers that could beused to prepare a crosslinked polymer in accordance with the invention.In this case, fatty acids or fatty acid esters that would not otherwisebe used in coatings and adhesives products can be converted into avaluable resource for such products.

A specific example of a cross-metathesis reaction described directlyabove would be the cross-metathesis reaction of a fatty acid ester withethene as shown below.

Those skilled in the art will appreciate that the cross-metathesisreactions described above also produce an ethylenically unsaturatedreaction by-product. However, unlike the ethylenically unsaturatedreaction by-products that can be produced during formation of thecrosslinked polymer, the desired terminal or near terminal ethylenicallyunsaturated compound and the ethylenically unsaturated reactionby-products produced during such cross-metathesis reactions cangenerally be readily separated from each other.

By “natural oils” is meant oils commonly referred to as vegetable oils,and even fish oil. Such oils must comprise at least one ethylenicallyunsaturated group, and will generally comprise triglycerides. Examplesof suitable natural oils include, but are not limited to, canola oil,soybean oil, flax or linseed oil, tung oil, castor oil, and combinationsthereof.

Unsaturated fatty acid and fatty acid esters derived from such oils canalso be used in accordance with the invention.

By “low molecular weight ethylenically unsaturated compound” in thecontext of a cross-metathesis reaction is meant a C₂-C₆ ethylenicallyunsaturated compound.

Cross-metathesis reactions using low molecular weight simple alkeneshave been studied for many years. Of the simple alkenes explored inthese cross-metathesis reactions, ethene, as employed in the reactionsdepicted above, has received the most attention. Cross-metathesisreactions involving ethene are generally referred to as ethenolysisreactions.

Despite considerable research being devoted to studying such ethenolysisreactions, there remain significant problems associated with using thistechnique to prepare terminal unsaturated compounds, and in particularterminal unsaturated carbonyl compounds. These problems can include poorconversion and selectivity, the need for relatively high catalystloadings, long reaction times and some limitations on the type offeedstocks.

One significant problem with ethenolysis reactions that has to dateproven difficult to overcome is the generation of a methylideneintermediate in the catalytic cycle. Ruthenium methylidene complexeshave been shown to have relatively low initiation rates in olefinmetathesis reactions. For reactions in which methylidene intermediatesare present, sustained metathesis activity can be achieved by increasingtemperature. However, this approach also increases the rate of catalystdecomposition resulting in the need for higher catalyst loadings.

A further problem associated with ethenolysis reactions is that theproducts of the reaction (i.e. terminal olefins) and the ethene cancompete with internal olefins present in the starting material inbinding to the metathesis catalysts. This results in long reactionstimes and also has an impact on catalyst loading as significantdecomposition of the catalyst can occur during the course of thereaction.

As mentioned, there can be some limitations on the type of feedstocksthat may be used in ethenolysis reactions. For example, natural oilsthat contain conjugated polyunsaturated fatty acids, such as tung oil,are typically poorly converted in ethenolysis reactions. This problemcan also extend to other polyunsaturated oils that are not conjugated.For example, ruthenium-based olefin metathesis catalysts have a tendencyto catalyse olefin isomerization reactions in addition to olefinmetathesis reactions, Thus, 1,4-dienes commonly found in polyunsaturatednatural oils can isomerise in the presence of the metathesis catalyst togive conjugated olefins and hence the same problems described above.

Accordingly, there remains a need to provide an alternative method forpreparing acyclic unsaturated compounds that can overcome or alleviateat least some of the disadvantages associated with the aforementionedethanolysis reactions.

The invention further provides a method of preparing near terminalethylenically unsaturated carbonyl compounds, which method comprisessubjecting a carbonyl compound comprising an acyclic ethylenicallyunsaturated group to a cross-metathesis reaction with substantially pure2-butene.

It has now been found that substantially pure 2-butene can be usedeffectively and efficiently in preparing near terminal ethylenicallyunsaturated carbonyl compounds. The 2-butene may be cis or trans, or acombination thereof. The use of 2-butene in cross metathesis reactionsto produce ethylenically unsaturated carbonyl compounds has beenreported. However, such reactions have afforded particularly low yields.Without wishing to be limited by theory, it is believed that commercialsources of 2-butene comprise sufficient quantities of impurities thatcan poison the olefin metathesis catalysts used in such reactions (e.g.ruthenium based metathesis catalysts), Such impurities are believed toat least comprise 1, 3-butadiene, a poison for acyclic metathesisreactions. Accordingly, cross metathesis reactions using 2-butene (i.e.butenolysis) to date have been inefficient and practically ineffective.

By using substantially pure 2-butene, cross-metathesis reactions can nowadvantageously be performed where the productive turn over number (TON)is greater than about 5,000, preferably greater than about 10,000, morepreferably greater than about 20,000, most preferably up to 90,000 orhigher.

By “substantially pure” 2-butene is meant that the 2-butene issufficiently free of impurities to enable turn over numbers of greaterthan about 5,000 to be achieved. Typically, impurities should be presentin an amount no greater than about 0.1 mol %, relative to 2-butene.

The use of 2-butene is believed to also advantageously avoid methylideneintermediates being formed during the catalytic cycle, thuscircumventing the problems associated with methylidene intermediates inethenolysis reactions. Another advantage to using 2-butene is that as aninternal ethylenically unsaturated compound it competes to a less extentwith unreacted ethylenically unsaturated carbonyl compounds to bind tothe catalyst compared with ethylene.

The conversion and selectivity of the butenolysis reactions can becontrolled by the ratio of 2-butene to the ethylenically unsaturatedcarbonyl compound. In order to achieve high selectivity and conversion alarge excess of 2-butene over the ethylenically unsaturated carbonylcompounds should be used, The reaction can be conducted with or withoutadditional solvent, and preferably either at elevated temperature (>1°C.) and pressure (>1 atm.) or at low temperature (<1° C.) andatmospheric pressure.

Those skilled in the art will appreciate that such butenolysis reactionswill afford near terminal ethylenically unsaturated carbonyl compoundsin which the ethylenically unsaturated group is located between thesecond and third atoms of a pendant group. In other words, theethylenically unsaturated group will be a penultimate terminalethylenically unsaturated group (i.e. R—C—C—C—C═C—C).

The butenolysis reaction in accordance with the invention mayconveniently be preformed using a diverse array of ethylenicallyunsaturated carbonyl compounds. By “ethylenically unsaturated carbonylcompound” is meant an ethylenically unsaturated compound that comprisesone or more carbonyl functional groups such as an ester, an amide, aketone, an aldehyde or a carboxylic acid. Having regard to the forgoing,those skilled in the art could readily select suitable ethylenicallyunsaturated carbonyl compounds for this purpose.

The butenolysis reaction in accordance with the invention mayconveniently be preformed using unsaturated natural oils, or fatty acidsor fatty acid esters derived therefrom, to prepare near terminalethylenically unsaturated carbonyl compounds. The butenolysis reactionis particularly suited for use in preparing branched polyunsaturatedmonomers that may be crosslinked in accordance with the invention. Forexample, the butenolysis reaction may be used to prepare branchedpolyunsaturated monomers from linseed oil as illustrated below.

The method of preparing a crosslinked polymer in accordance withinvention can advantageously be performed in numerous ways and under avariety of conditions. Such versatility stems in part from the abilityto provide the branched polyunsaturated monomers in either a liquid or asolid form, and also the ability to select the monomers such that theycan be polymerised by the metathesis reaction at ambient temperatures.

To accelerate the rate of crosslinking and produce tightly crosslinkedand inert coatings, industrial processes, such as the coating ofautomotive bodies or continuous coil with crosslinkable coatings, areoften performed at elevated temperature (i.e. up to about 240° C.).However, for temperature sensitive substrates or consumer applicationswhere the use of high temperature is not convenient or not possible, itis highly desirable to employ crosslinking reactions that are accessibleat room temperature or only with moderate degree heating (i.e.temperatures less than 100° C.). Such crosslinking reactions will ofcourse still be accelerated if more heat is applied, but the mainadvantage is that the reactions are available for consumer application.The crosslinking method in accordance with the invention is particularlywell suited for such consumer applications.

In performing the method of the invention, the necessary reagents may beprovided in a variety of different two-part systems. The coatings andadhesives products of the invention may be conveniently provided in theform of such two-part curable systems.

A simple two-part system may comprise a first part which comprisesbranched polyunsaturated monomers suitable for reaction in accordancewith the present invention, and a second part which comprises ametathesis catalyst. The formulations of each part can readily be mixedprior to application to enable crosslinking to occur post-applicationthrough a metathesis mediated reaction pathway.

One advantage such two-part systems may provide over conventional twopart systems is that once the two parts are mixed, the crosslinkingreaction can be retarded simply by enclosing the mixture in a sealedcontainer. By confining the mixture in this way, volatile alkeneby-products are restricted from leaving the reaction environment and themetathesis reaction can be retarded. This in turn can extend theproducts workable application time post mixing.

Depending upon the nature of the monomer and catalyst, crosslinking mayoccur at ambient temperatures, or it may be necessary to apply heat tothe mixed two-part formulation to promote crosslinking. An example ofwhere it may be necessary to apply heat to promote crosslinking is wherethe monomer is provided in solid form. In solid form, the monomer can beconveniently powdered and applied to a substrate using conventionalpowder coating technology. The catalyst can then be applied to themonomer by a technique such as spraying. Alternatively, due to therebeing limited reactivity between the catalyst and the solid monomer, thecatalyst may be combined with the powdered monomer before it is appliedto the substrate. In order to promote crosslinking, the catalyst/monomercombination can be heated by well known methods such as inferred (IR)irradiation. Under these circumstances, sufficient heat is generallyapplied to cause the monomer to melt.

As an alternative two-part system, the first part may comprise branchedpolyunsaturated monomers and acyclic diene monomers, and the second partmay comprise the metathesis catalyst. This two-part system may beutilised in much the same way as the system discussed above. However, inthis case the presence of the acyclic diene monomers providesconsiderable flexibility in being able to adjust the composition andarchitecture of the resulting crosslinked polymer. Notably, thecrosslink density of the resulting crosslinked polymer can be readilyadjusted. For example, by providing the first part with diene monomersthe crosslink density of the resulting crosslinked polymer can bereduced. Conversely, by providing the first part with little or no dienemonomers the crosslink density of the resulting crosslinked polymer canbe increased.

Accordingly, the method of the invention may further comprisepolymerising acyclic diene monomers by the metathesis polymerisationreaction.

It should also be noted that the crosslink density of the crosslinkedpolymers prepared in accordance with the invention can also be varied bychanging the nature of the branched polyunsaturated monomers. In thiscase, by having the acyclic ethylenically unsaturated groups of themonomer in closer proximity to each other the crosslink density of theresulting crosslinked polymer will generally be higher than if theunsaturated groups were more spaced apart.

Thus, through variation of the nature of the branched polyunsaturatedmonomer and the use of acyclic diene monomers, the method provides forconsiderable flexibility in being able to adjust the composition andarchitecture of the resulting crosslinked polymer.

When used in conjunction with the branched polyunsaturated monomers inpreparing the crosslinked polymers, the acyclic diene monomers shouldalso react with the metathesis catalyst during the crosslinking process.Accordingly, the diene monomers must have at least two ethylenicallyunsaturated groups that are susceptible to undergoing polymerisation bya metathesis reaction. Suitable acyclic diene monomers are generallywell known and readily available. In particular, those monomers suitablefor use in a conventional ADMET polymerisation may be used as acyclicdiene monomers.

Acyclic diene monomers used in conjunction with the branchedpolyunsaturated monomers can be in either liquid or solid form. Whereboth the branched acyclic polyunsaturated monomer and the diene monomerare in solid form, both monomers can conveniently be melt mixed, forexample by extrusion, and subsequently powdered for use in a powdercoating process as described above.

An alternative two-part system may also comprise a first part whichcomprises branched polyunsaturated monomers suitable for reaction inaccordance with the present invention, and a second part which comprisesa polymer prepared by ADMET polymerisation. In this case, it isimportant that the ADMET derived polymer retains an active catalystcomponent. By “retains an active catalyst component” is meant that thepolymer reaction product of the ADMET polymerisation reaction hasassociated with it metathesis catalyst which is capable of promotingfurther polymerisation reactions.

In this particular two-part system, the formulations of each part may bemixed prior to application to enable to crosslinking occurpost-application through a metathesis mediated reaction pathway.However, unlike the previous two-part systems, the catalyst component isprovided by an ADMET derived polymer. In this case, the catalyst ineffect remains dormant until the components of each part are combined.This two-part system may be utilised in much the same way as the systemsdescribed above. For example, the monomers and ADMET derived polymer maybe provided in solid form and applied by powder coating techniques.Alternatively, the monomers and/or ADMET derived polymer may be solvatedwith a suitable solvent to provide for a liquid curable system.

The method of preparing a crosslinked polymer in accordance with theinvention may be performed as a bulk polymerisation or in an organicsolvent. By providing the branched polyunsaturated monomers as lowviscous liquids, or in solid form, the two-part systems described abovemay be formulated using little if no organic solvent. The ability to uselittle if no organic solvent in such systems is a particularlyadvantageous given the onerous legislative requirements regarding thepermissible volatile organic content (VOC) of coating and adhesiveproducts that apply in many countries.

The method of crosslinking polymers in accordance with the invention canbe readily applied to provide effective coatings and adhesives. Thecoating and adhesives in accordance with the invention comprise branchedpolyunsaturated monomers that contain acyclic ethylenically unsaturatedgroups that are capable of undergoing polymerisation by a metathesisreaction to form a crosslinked polymer, and an olefin metathesiscatalyst. Those skilled in the art will have an understanding of othersuitable formulation components that may also be included in the coatingand adhesives. Examples of such formulation components include, but arenot limited to, thickeners, antifungal agents, UV absorbers, extenders,pigments and tinting agents.

The cured product formed from the coatings and adhesives in accordancewith the invention may comprise polymer material not formed through themetathesis crosslinking reaction. Accordingly, the coatings andadhesives may be formulated as a blend with other polymers and/ormonomers that are not formed from or take part in the metathesispolymerisation reaction.

A notable advantage of the coatings and adhesives in accordance with theinvention is that the products crosslinked polymer structure is notformed via autoxidation. As previously mentioned, the process ofautoxidation can continue for a long period of time (i.e. post drying ofthe coating or adhesive) and may result in degradation of the physicalproperties of the coating or adhesive. For example, in oil based paintsdegradation of the crosslinked polymer can lead to pigment particles atthe surface of the paint film becoming exposed and result in a problemknown as chalking. Oil based paints are also prone to yellowing due tothe presence or formation of residual conjugated unsaturation in thepolymer that forms the paint film.

Unlike the progressive nature of autoxidation, the metathesis mediatedreaction pathway that operates in the crosslinking method of theinvention occurs within a finite time frame uniformly throughout thecomposition. Furthermore, feedstock monomers for the metathesiscrosslinking reactions are unlikely to contain or give rise to aresidual conjugated unsaturation in the resulting crosslinked polymerproduct. Thus, the crosslinked polymer products in accordance with theinvention will typically maintain their physical properties and be lessprone to yellowing over time compared with products formed byconventional means.

The present invention involves the use of an olefin metathesis catalyst.Those skilled in the art could readily select and obtain suitablecatalysts to perform the invention. Examples of suitable olefinmetathesis catalyst include, but are not limited to, Grubbs Catalyst 1stgeneration, or Benzylidene-bis(tricyclohexylphosphine)dichlororuthenium,Grubbs Catalyst 2nd Generation, orBenzylidene[1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro(tricyclohexylphosphine)ruthenium,and Hoveyda-Grubbs Catalyst 2nd Generation, or 1,3-Bis-(2,4,6-trimethylphenyl)-2-imidazolidinylidene)dichloro(o-isopropoxyphenylmethylene)ruthenium.

For butenolysis reactions and cross-linking with butenolysis products,Grubbs Catalyst 2nd Generation and Hoveyda-Grubbs Catalyst 2ndGeneration are preferred.

The olefin metathesis catalyst may be provided in any suitable form thatenables it to promote polymerisation. For example, the catalyst may becombined with a suitable carrier material such as a solvent or perhaps asolid and formed into a tablet. It will be appreciated that any suchcarrier material should be compatible with other components of thecurable systems.

EXAMPLES Example 1 Butenolysis of Triolein

A schlenk tube equipped with a magnetic stirrer bar was evacuated thenfilled with argon and placed in a methanol bath which was cooled to −5°C. The tube was charged with cis-2-butene (1.30 g, 23.2 mmol) andtriolein (0.75 mL, 7.7 mmol). A solution of Hoveyda-Grubbs SecondGeneration Catalyst (0.145 μg, 2.32 nmol) in dichloromethane (10 μL) wasadded to the tube and the mixture was stirred using a magnetic stirrerfor 256 minutes. After this time the reaction was quenched by additionof ethyl vinyl ether (500 μL). A sample of the product wastrans-esterified with methanol by conventional means and analysis of thetrans-esterification product by Gas Chromatography (GC) showed aconversion of >90% the oleic chains to 9-undecenoic chains. Thisconversion equates to a TON of >90,000 for the catalyst.

Example 2 Butenolysis of methyl oleate with 2-butene of Varying Purity

Schlenk tubes equipped with a magnetic stirrer bar was evacuated thenfilled with argon and placed in a methanol bath which was cooled to −5°C. Various samples were prepared using samples of 2-butene from varioussources;

Sample A (comparative): cis+trans 2-butene (contains 2.6% of 1,3butadiene)

Sample B: cis-2-butene (free of 1,3 butadiene)

Sample C (comparative): cis 2-butene (free of 1,3 butadiene) doped with2% butadiene

The quantity of 2-butene added in each case was the same (1.30 g, 23.2mmol). A quantity of singly distilled methyl oleate (1.45 mg, 4.88 mmol)and a solution of Hoveyda-Grubbs Second Generation Catalyst (0.145 μg,2.32 nmol) in dichloromethane (10 μL) was added to the tube and themixture was stirred using a magnetic stirrer for 256 minutes. After thistime the reaction was quenched by addition of ethyl vinyl ether (500μL). The samples were analysed by GC and the degree of conversion of theoleic chains to 9-undecenoic chains compared.

Results:

Sample A trace << 1% conversion Sample B >90% conversion Sample C trace<< 1% conversion

Example 3 Butenolysis of methyl oleate

A stainless steel autoclave with a glass liner was equipped with amagnetic stirrer bar and charged with ethyl oleate (0.34 g, 1.1 mmol)and Second Generation Grubbs Catalyst (9.3 mg, 0.11 μmol). The autoclaveflushed with argon. The autoclave was evacuated and then pressurisedwith cis-2-butene to a pressure of 15 psi. The autoclave was heated at60° C. with stirring overnight. The pressure was then released and ethylvinyl ether (50 μL) added to the reaction mixture. A sample of theproduct was trans-esterified with methanol by conventional means andanalysis of the trans-esterification product by GC showed a conversionof >85% of the oleic chains to 9-undecenoic chains.

Example 4 Butenolysis of Canola Oil

A 2 L round bottomed flask equipped with a magnetic stirrer bar wasimmersed in a methanol bath. The flask was charged with canola oil(80.97 g), then evacuated and the oil stirred rapidly for 1 hour. Theflask was then filled with argon and the methanol bath was cooled to −7°C. The flask was then charged with cis+ trans-2-butene (204.5 g, 3.65mol). A solution Hoveyda-Grubbs Second Generation Catalyst (11.4 mg,0.18 μmol) in dichloromethane (1 mL) was added to the flask and themixture was stirred using a magnetic stirrer for 64 minutes. After thistime tricyclohexylphosphine (0.15 g) was added to the mixture. Thetemperature of the bath was raised slowly to ˜40° C. and the volatilescollected by distillation. A small sample of the product wastrans-esterified with methanol by conventional means and analysis of thetrans-esterification product by GC showed a conversion of >95% theunsaturated fatty acid chains to 9-undecenoic chains.

Example 5

Butenolysis of a Soya-Based alkyd Resin

A 2 L round bottomed flask equipped with a magnetic stirrer bar wasimmersed in a methanol bath cooled to ˜10° C. The flask was evacuatedand filled with argon. The flask was charged with a de-gassed solutionof a soya-based alkyd resin (90 g) in dichloromethane (100 mL), cis+trans-2-butene (166 g, 2.96 mol) and Hoveyda-Grubbs Second GenerationCatalyst (0.10 g, 16.0 mmol). The mixture was stirred using a magneticstirrer for ˜90 minutes. After this time additional Hoveyda-GrubbsSecond Generation Catalyst (0.10 g, 16.0 mmol) was added to the reactionand stirring was continued for a further 60 minutes.Tricyclohexylphosphine (0.10 g) was added to the mixture. Thetemperature of the bath was raised slowly to room temperature and thevolatiles were collected by distillation. Air was bubbled through theremaining solution overnight. A small sample of the product wastrans-esterified with methanol by conventional means and analysis of thetrans-esterification product by GC showed a conversion of >90% theunsaturated fatty acid chains to undec-9-enoic chains, Additionalvolatile compounds were removed from the product by heating the productat 150° C. in a high vacuum for 15 minutes.

Example 6 Preparation of2,2-bis((undec-10-enoyloxy)methyl)propane-1,3-diyl diundec-10-enoate

Trimethylolpropane (2.73 g, 20.34 mmol), undecenylenic acid (15.0 g,81.39 mmol, 4 equiv.) and DMAP (0.99 g, 8.136 mmol, 0.4 equiv.) weredissolved in tetrahydrofuran (150 ml) and the mixture was cooled to 0°C. DCC (16.77 g, 81.39 mmol, 4 equiv.) in tetrahydrofuran (45 ml) wasadded drop-wise to the mixture and kept at 0° C. for 30 mins thenallowed to warm to 20° C. and stirred for 3 days. The mixture wasfiltered (to remove N,N-dicyclohexyl urea) to remove precipitate. Theremaining clear liquid was reduced under partial pressure. The residuewas taken up in ether, washed with sodium carbonate (10% aqueoussolution), brine, dried over magnesium sulfate, filtered and reducedunder partial pressure. The crude material was purified by flashchromatography (ethyl acetate/hexane 5/95) to give 9.55 g (74%) ofethane-1,1,1-triyl triundec-10-enoate as a yellow oil; IR (film) 3467,3076, 2922, 2855, 2120, 1746, 1640, 1464, 1417, 1386, 1355, 1236, 1158,1116, 1056, 994, 909, 783, 724 cm⁻¹; ¹H NMR (CDCl₃): δ=5.90-5.72 (m,3H), 5,04-4.87 (m, 6H), 4.00 (s, 6H), 2.28 (t, 6H, J=2.26 Hz), 2.07-1.99(m, 6H), 1.62-1.55 (m, 6H), 1.52-1.43 (m, 2H), 1.42-1.34 (m, 30H), 0.88(t, 3H, J=2.12 Hz); ¹³C NMR (CDCl₃): δ=173.2, 138.9, 114.0, 63.6, 40.5,34.1, 33.6, 29.2, 29.1, 29.0, 28.9, 28.7, 24.8, 23.0, 7.2; MS-ESI m/z655.6 (M+Na⁺). Anal. Calcd for C₃₉H₆₈O₆: C, 74.00; H, 10.83. Found; C,73.98; H, 11.01.

Example 7 Preparation of2-ethyl-2-((undec-10-enoyloxy)methyl)propane-1,3-diyl diundec-10-enoate

Pentaerythrilol (2.94 g, 21.59 mmol), undecenoic acid (20.0 g, 108.53mmol, 5 equiv.) and DMAP (1.32 g, 10.85 mmol, 0.5 equiv.) were dissolvedin THF (150 ml) and the mixture was cooled to 0° C. DCC (22.28 g, 108.53mmol, 5 equiv.) in THF (50 ml) was added dropwise to the mixture andkept at 0° C. for 30 minutes then allowed to warm to 20° C. and stirredfor 3 days. The mixture was filtered then reduced under partialpressure. The residue was taken up in ether (200 ml) and washed withNa₂CO₃ (10% aqueous solution), brine, dried over MgSO₄, filtered andreduced under partial pressure. The crude material was purified by flashchromatography (EtOAc/Hexane 5/95) to give 12.65 g (72%) of2-ethyl-2-((undec-10-enoyloxy)methyl)propane-1,3-diyl as a yellow oil;IR (flim) 3469, 3076, 2926, 2855, 1745, 1640, 1466, 1416, 1389, 1355,1235, 1157, 1116, 994, 909, 724 cm⁻¹; ¹H NMR (CDCl₃): δ=5.86-5.72 (m,41-1), 5.01-4.89 (m, 8H), 4.10 (s, 8H, CCH₂O), 2.31-2.26 (m, 8H),2.06-1.99 (m, 8H), 1.63-1.53 (m, 8H), 1.42-1.22 (m, 40H); ¹³C NMR(CDCl₃): δ=173.1, 139.0, 114.1, 62.1, 41.83, 34.0, 33.7, 29.2, 29.1,29.0, 28.9, 28.8, 24.8; MS-ESI m/z 801.8 (M+H)⁺. Anal. Caled. forC₄₉H₈₄O₈: C, 73.46; H, 10.57. Found: C, 73.39; H, 10.65.

Example 8 Preparation of the diester of biphenol A and 10-undecenoicacid

2,2-diallybisphenol A (1.577 g, 5.11 mmol) and undecenoic acid chloride(3.11 g, 15.34 mmol, 3 equiv.) were combined together and the mixturewas heated at 60° C. for 16 hours. The mixture was taken up in ether (50ml) and washed with sodium hydrogen carbonate (saturated aqueoussolution) (3×50 ml) then washed with brine (2×40 ml), dried overanhydrous magnesium sulfate, filtered and reduced under partialpressure. The crude material was purified by flash chromatography (ethylacetate/hexane 5/95) to give 3.11 g (95%) of the product as a paleyellow oil; ¹H NMR (CDCl₃): δ=7.09-7.04 (m, 4H), 6.92-6,90 (m, 2H),5.90-5.77 (m, 4H), 5.04-4.92 (m, 8H), 6.50 (d, 4H, J=6.3 Hz), 2.54 (t,4H, J=7.5 Hz), 2.08-2.01 (m, 4H), 1.77-1.70 (m), 1.64 (s, 6H), 1.43-1.32(bs, 24H); ¹³C NMR (CDCl₃): δ=172.8, 148.3, 147.1, 139.4, 136.3, 131.2,128.9, 126.2, 121.9, 116.7, 114.4, 42.7, 35.1, 34.6, 34.0, 31.2, 29.5,29.4, 29.3, 29.2, 29.1, 25.2; MS-ESI m/z (M+H)⁺. Anal. Calcd. forC₄₃H₆₀O₄: C, 80.58; H, 9.44. Found: C, 78.81; H, 9.30.

Example 9 Cross-Linking of the butenolysis Product of Canola Oil to Givea Film

Simple alkenes were removed from the butenolysis product of canola oil(e.g. the product derived from Stage 1 of Example 4) by vacuumdistillation leaving a pale yellow oil. A sample of this oil (0.46 g)was mixed with titanium dioxide (0.29 g) and ground to a homogeneousmixture. This mixture was placed on a microscope slide and a solution ofHoveyda-Grubbs Second Generation Catalyst (15 mg) in dichloromethane (10μL) added and mixed thoroughly. The mixture was spread to cover an areaof 40×60 mm. After 1 hour the film was found to have set to a solid filmand have lost 0.025 g in mass. The film was found to be insoluble in thefollowing solvents: water; methanol; acetone; ethyl acetate; hexane;toluene.

Example 10 Cross-Linking of an alkyd Resin Based on 9-undecenoic acid toGive a Film

A sample of the product of Example 5 (1.0 g) was ground to a homogeneousmixture with titanium dioxide (0.63 g) and toluene 0.5 mL.Hoveyda-Grubbs Second Generation Catalyst (15 mg) was mixed thoroughlyinto the mixture, which was then painted onto a microscope slide. After10 minutes the film had set to give a glossy surface. This film whichwas initially slightly soft, became progressively harder over the next12 hours to finally give a hard tough film which adhered well to theglass. The film was found to be insoluble in the following solvents:water; methanol; acetone; ethyl acetate; hexane; toluene.

Colour Comparison

A film derived from the experimental white pigmented paint was comparedto a film derived from a commercially available white pigmented alkydpaint (Dulux High Gloss Enamel). Films of the experimental sample andcommercial product were cast onto a sealed panel using a #40 wiredrawdown bar and the films dried fully over 48 hours. The colourdifference between experimental and commercial films was compared to thesame reference white tile and the colour difference coordinatescalculated using a CIE1976 colour system. Aging of the samples was thenaccelerated by taking the same panel and taping it to the inside of ametal can having a close fitting lid into which 5 ml of a 10% solutionof ammonium hydroxide was placed to saturate the atmosphere in the can.The panel was exposed to these conditions for 48 hours.

Results:

Delta L Delta a Delta b Example 10 Before ammonia exposure −0.70 0.030.47 After ammonia exposure −0.35 −0.25 1.33 Commercial Before ammoniaexposure 0.10 −0.69 1.77 sample After ammonia exposure −2.69 −0.42 12.74(comparative)

The substantial difference in yellowness (+1.30) between theexperimental sample and the comparative sample prior to being exposed toammonia was clearly evident by eye. The effect of ammonia exposure is atest well known as correlating with the tendency of conventional enamelsto yellow over time. After ammonia exposure, the comparative sampleshowed significantly more yellowing (+11.41). Due to the absence ofautoxidation in the film derived from the experimental sample, theseresults are expected to reflect the difference that would be attainedthrough natural exposure over time. In other words, the crosslinked filmin accordance with the invention is expected to undergo little if noyellowing over time.

Example 11 Cross-Linking of2-ethyl-2-((undee-10-enoyloxy)methyl)propane-1,3-diyl diundec-10-enoateto Give a Film

First Generation Grubbs Catalyst (10 mg) was dissolved in a minimumvolume of dichloromethane and mixed with2-ethyl-2-((undec-10-enoyloxy)methyl)propane-1,3-diyl diundec-10-enoate(0.80 g). The mixture was spread onto a petridish. After 17 hours themixture had become a hard and rubbery film.

Throughout this specification and the claims which follow, unless thecontext requires otherwise, the word “comprise”, and variations such as“comprises” and “comprising”, will be understood to imply the inclusionof a stated integer or step or group of integers or steps but not theexclusion of any other integer or step or group of integers or steps.

The reference in this specification to any prior publication (orinformation derived from it), or to any matter which is known, is not,and should not be taken as an acknowledgment or admission or any form ofsuggestion that that prior publication (or information derived from it)or known matter forms part of the common general knowledge in the fieldof endeavour to which this specification relates.

1-21. (canceled)
 22. A coating or adhesive product comprising: (1)branched polyunsaturated monomers that: (a) comprise at least a generalstructural unit (I):BR¹R²R³   (1) where B represents an atom or core, and where each moietyR¹, R² and R³, which may be the same or different, contains at least oneacyclic ethylenically unsaturated group which (i) is located within 6atoms from the end of the moiety, and (ii) is capable of undergoingpolymerization by a metathesis reaction contain terminal or nearterminal acyclic ethylenically unsaturated groups that are capable ofundergoing polymerisation by a metathesis reaction to form a crosslinkedpolymer to afford a crosslinked polymer and substantially nonon-volatile ethylenically unsaturated by-products, and (b) are, or arederived from, a natural oil, and (2) an olefin metathesis catalyst. 23.The coating or adhesive product according to claim 22 in the form of atwo-part curable system, wherein the branched polyunsaturated monomersare provided in the first part and the olefin metathesis catalyst isprovided in the second part.
 24. The coating or adhesive productaccording to claim 23, wherein the first part further comprises acyclicdiene monomers.
 25. The coating or adhesive product according to claim23, wherein the second part further comprises a polymer formed throughacyclic diene metathesis polymerisation.
 26. The coating or adhesiveproduct according to claim 22, wherein the olefin metathesis catalyst isselected from Grubbs catalyst first and second generation.
 27. A methodof preparing near terminal ethylenically unsaturated carbonyl compounds,which method comprises subjecting a carbonyl compound comprising anacyclic ethylenically unsaturated group to a cross-metathesis reactionwith substantially pure 2-butene.
 28. The method according to claim 27,wherein the carbonyl compound comprises one or more carbonyl functionalgroups selected from an ester, an amide, a ketone an aldehyde, acarboxylic acid and combinations thereof.
 29. The method according toclaim 27, wherein the cross-metathesis reaction provides for aproductive turn over number of greater than about 10,000.
 30. The methodaccording to claim 27, wherein the carbonyl compound is a natural oil, afatty acid derived from a natural oil, or a fatty acid ester derivedfrom a natural oil.